Recently, much attention has been paid to a functional sheet on whose surface a high aspect ratio structure such as a microneedle is formed.
In the medical technology field, there is proposed a needle array sheet on whose surface microneedles, which are needle-like protrusions, are formed as a percutaneous sheet for effectively administering medicaments to a human body through skin. The percutaneous sheet is required to administer medicaments to a human body without causing pain, and thus the microneedle is preferably narrow, has a high aspect ratio, and makes the tip as sharp as possible.
The needle array sheet can be fabricated by cast molding, injection molding, or the like, using a concave array mold in which a needle-like recess, which is a reversed shape of a microneedle, is formed. In general, the concave array mold having a needle-like recess is fabricated by transfer-molding using a template on which a needle-like protrusion is formed, but the template can be fabricated by the following method.
For example, Patent Documents 1 to 3 disclose methods of dry-etching a substrate through a resist pattern formed on a substrate surface.
Patent Document 4 discloses a method of cutting or grinding a metal substrate using a diamond tool.
Further, Patent Document 5 discloses a method of fabricating a transfer mold such as an epoxy resin having a protrusion, using a master mold in which a recess is formed on a metal fine particle dispersed polymer film by laser processing.    Patent Document 1: National Publication of International Patent Application No. 2002-517300    Patent Document 2: National Publication of International Patent Application No. 2004-526581    Patent Document 3: Japanese Patent Application Laid-Open No. 2006-341089    Patent Document 4: National Publication of International Patent Application No. 2007-523771    Patent Document 5: Japanese Patent Application Laid-Open No. 2006-264288